<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>发布订阅者模式</title>
</head>

<body>
    <script>
        //事件触发器
        class EventEmitter {
            constructor() {
                // {'click':[fn1,fn2],'change':[fn1,fn2]}
                this.subs = Object.create(null)
            }

            //注册事件
            $on(eventType, handler) {
                this.subs[eventType] = this.subs[eventType]||[]
                this.subs[eventType].push(handler)
            }

            //触发事件
            $emit(eventType) {
                if(this.subs[eventType]){
                    this.subs[eventType].forEach(handler => {
                        handler()
                    });
                }
            }
        }

        //测试
        let em = new EventEmitter()
        em.$on('click',()=>{
            console.log('click1');
            
        })
        em.$on('click',()=>{
            console.log('click2');
            
        })
        em.$emit('click')
    </script>
</body>

</html>